The street, bisecting the site of the long-demolished Jacob Ruppert and Co. Knickerbocker Brewery, has been closed to vehicular traffic for 42 years and serves as an open-air community space.

Officially named James Cagney Place, for the song-and-dance man who grew up on East 96th Street, it is the hill where a 5-year boy named Ben

Kallos once played in the puddles on a rainy day with other local kids.

Now, he’s the 36-year-old City Council member representing the area, and he’s never stopped coming to the block — a “staple of childhood on the Upper East Side,” he calls it — especially for sledding after a snow.

“This portion of East 91st Street has been a closed play street for longer than I have been alive,” Kallos added.

In recent years, that status appeared to be in doubt: A possible threat to the landscaped, red-brick pedestrian plaza-and-walkway suddenly loomed on the horizon — the city’s planned Marine Transfer Station.